empowered (and clearly they must already have this authority, but they don't do this much at all that I have seen) to simply on-the-spot ticket various driving offenses as they saw them:

Driving on shoulder and cutting into line
Creating a third lane where there is none
Driving with children in front seat
Talking on mobile
Not wearing seat belt

And I am in agreement that visible radars help reduce speeding overall. But maybe there IS some purpose to having a few hidden ones across town, that move and get repositioned frequently; otherwise, you just get the cars that simply brake/slow when they see the camera, then speed up again once they've passed it.

"Most plain girls are virtuous because of the scarcity of opportunity to be otherwise."
-- Maya Angelou